The invention relates to the field of electronic devices which can communicate with a reader, and more precisely to the field of devices communicating with readers.
The invention is more precisely directed to devices equipped with single-chip microcontrollers which can be smart-cards, embedded secure elements, USB tokens, micro secure digital cards, smart phones, smart watches, or any smart token.
Taking smart cards as an example, smart cards usually comprise a processor which, when the card is electrically powered, executes various applications through a platform acting as operating system. Smart cards are powered by the readers either using electrical contacts arranged on the cards (contact mode) or using near field communication technology (contactless mode).
Traditionally, when a smart card receives electrical power, several tests are executed. These tests are known to the skilled person as “power-up self-tests”. For example, power-up self-test may include the testing of cryptographic functions. Cryptographic functions are generally implemented in a cryptographic module of a smart card, and the testing is carried out directly by the smart card (i.e. without receiving any command from the reader).
If these cryptographic functions behave abnormally, it can be deduced that the smart card is being attacked or that the smart card is damaged or at least that the cryptographic module of the smart card performing these functions is damaged.
The North-American standard FIPS 140 (“Federal Information Processing Standards”) defines a plurality of such power-up self-tests. The power-up self-tests required in the FIPS 140 standard can require up to 500 milliseconds of execution time.
This duration is too long when a smart card is used in an environment where, for example, several users will use their card one after the other. This may be the case in a public transportation system (bus or metro) wherein at peak time, in order to avoid any congestion, the total time required to carry out the processing of a user (or transaction time) should not exceed 200 milliseconds.
Another example requiring a short transaction time is the use of smart cards for identifying users entering a building (usually known under the acronym PACS: Physical Access Control System). When used in a corporate environment, a smart card requiring more than 500 milliseconds of power-up self-tests leads to a long line of employees outside of a building which leads to a loss in productivity for the employer.
The duration of power-up self-tests is unacceptable.
The invention notably aims at overcoming this drawback.